<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
  <style>
    #test{
      width: 50%;
      height: 20rem;
    }
    #testa{
      margin-left: 100px;
    }
  </style>
</head>
<body>
<div id="test"><a id="testa" href="#">lalala</a></div>
</body>
</html>